I have an issue for registration. I compare configuration of a functional Gateway(registered) and this one with trouble and they are identical

so I make a tcpdump on my proxy server(10.12.114.173) to see what's going on ... we can see the gateway (sip:7855@10.11.50.215) try T1 sip register to the proxy and the proxy redirect the register packet to the asterisk server (10.11.1.116)

the asterisk server reply with a 401 status and a WWW-Authenticate header at the proxy and the proxy redirect the packet to the gateway.

Everything seems normal so far.

but from here I don't find (in comparison to the functional gateway) the Authorization Header reply.

I have just 7 retries (default value configuring in my gateway) from the malfunctioning gateway to the proxy and proxy resend the packet with WWW-Authenticate header to the gateway.